Responses of competitive understorey species to spatial environmental gradients inaccurately explain temporal changes

Understorey plant communities play a key role in the functioning of forest ecosystems. Under favourable environmental conditions, competitive understorey species may develop high abundances and influence important ecosystem processes such as tree regeneration. Thus, understanding and predicting the response of competitive understorey species as a function of changing environmental conditions is important for forest managers. In the absence of sufficient temporal data to quantify actual vegetation changes, space-for-time (SFT) substitution is often used, i.e. studies that use environmental gradients across space to infer vegetation responses to environmental change over time. Here we assess the validity of such SFT approaches and analysed 36 resurvey studies from ancient forests with low levels of recent disturbances across temperate Europe to assess how six competitive understorey plant species respond to gradients of overstorey cover, soil conditions, atmospheric N deposition and climatic conditions over space and time. The combination of historical and contemporary surveys allows (i) to test if observed contemporary patterns across space are consistent at the time of the historical survey, and, crucially, (ii) to assess whether changes in abundance over time given recorded environmental change match expectations from patterns recorded along environmental gradients in space. We found consistent spatial relationships at the two periods: local variation in soil variables and overstorey cover were the best predictors of individual species’ cover while interregional variation in coarse-scale variables, i.e. N deposition and climate, was less important. However, we found that our SFT approach could not accurately explain the large variation in abundance changes over time. We thus recommend to be cautious when using SFT substitution to infer species responses to temporal changes.</p

Forest microclimate dynamics drive plant responses to warming

Climate warming is causing a shift in biological communities in favor of warm-affinity species (i.e., thermophilization). Species responses often lag behind climate warming, but the reasons for such lags remain largely unknown. Here, we analyzed multidecadal understory microclimate dynamics in European forests and show that thermophilization and the climatic lag in forest plant communities are primarily controlled by microclimate. Increasing tree canopy cover reduces warming rates inside forests, but loss of canopy cover leads to increased local heat that exacerbates the disequilibrium between community responses and climate change. Reciprocal effects between plants and microclimates are key to understanding the response of forest biodiversity and functioning to climate and land-use changes

Replacements of small- by large-ranged species scale up to diversity loss in Europe’s temperate forest biome

The loss of biodiversity at the global scale has been difficult to reconcile with observations of no net loss at local scales. Vegetation surveys across European temperate forests show that this may be explained by the replacement of small-ranged species with large-ranged ones, driven by nitrogen deposition. Biodiversity time series reveal global losses and accelerated redistributions of species, but no net loss in local species richness. To better understand how these patterns are linked, we quantify how individual species trajectories scale up to diversity changes using data from 68 vegetation resurvey studies of seminatural forests in Europe. Herb-layer species with small geographic ranges are being replaced by more widely distributed species, and our results suggest that this is due less to species abundances than to species nitrogen niches. Nitrogen deposition accelerates the extinctions of small-ranged, nitrogen-efficient plants and colonization by broadly distributed, nitrogen-demanding plants (including non-natives). Despite no net change in species richness at the spatial scale of a study site, the losses of small-ranged species reduce biome-scale (gamma) diversity. These results provide one mechanism to explain the directional replacement of small-ranged species within sites and thus explain patterns of biodiversity change across spatial scales

Observer and relocation errors matter in resurveys of historical vegetation plots

Aim: Revisits of non-permanent, relocatable plots first surveyed several decades ago offer a direct way to observe vegetation change and form a unique and increasingly used source of information for global change research. Despite the important insights that can be obtained from resurveying these quasi-permanent vegetation plots, their use is prone to both observer and relocation errors. Studying the combined effects of both error types is important since they will play out together in practice and it is yet unknown to what extent observed vegetation changes are influenced by these errors. Methods: We designed a study that mimicked all steps in a resurvey study and that allowed determination of the magnitude of observer errors only vs the joint observer and relocation errors. Communities of vascular plants growing in the understorey of temperate forests were selected as study system. Ten regions in Europe were covered to explore generality across contexts and 50 observers were involved, which deliberately differed in their experience in making vegetation records. Results: The mean geographic distance between plots in the observer+relocation error data set was 24m. The mean relative difference in species richness in the observer error and the observer+relocation data set was 15% and 21%, respectively. The mean pseudo-turnover between the five records at a quasi-permanent plot location was on average 0.21 and 0.35 for the observer error and observer+relocation error data sets, respectively. More detailed analyses of the compositional variation showed that the nestedness and turnover components were of equal importance in the observer data set, whereas turnover was much more important than nestedness in the observer+relocation data set. Interestingly, the differences between the observer and the observer+relocation data sets largely disappeared when looking at temporal change: both the changes in species richness and species composition over time were very similar in these data sets. Conclusions: Our results demonstrate that observer and relocation errors are non-negligible when resurveying quasi-permanent plots. A careful interpretation of the results of resurvey studies is warranted, especially when changes are assessed based on a low number of plots. We conclude by listing measures that should be taken to maximally increase the precision and the strength of the inferences drawn from vegetation resurveys

Unexpected westward range shifts in European forest plants link to nitrogen deposition

Climate change is commonly assumed to induce species’ range shifts toward the poles. Yet, other environmental changes may affect the geographical distribution of species in unexpected ways. Here, we quantify multidecadal shifts in the distribution of European forest plants and link these shifts to key drivers of forest biodiversity change: climate change, atmospheric deposition (nitrogen and sulfur), and forest canopy dynamics. Surprisingly, westward distribution shifts were 2.6 times more likely than northward ones. Not climate change, but nitrogen-mediated colonization events, possibly facilitated by the recovery from past acidifying deposition, best explain westward movements. Biodiversity redistribution patterns appear complex and are more likely driven by the interplay among several environmental changes than due to the exclusive effects of climate change alone

Diversity, distribution and conservation status of acidophilous and thermophilous oak forests (Cl. Quercetea robori-petraeae, O. Quercetalia pubescenti-petraeae) in the Sudety Mts and their foreland - abstract of phd thesis

<p>This is an abstract of my phd thesis in which I focused on diversity of oak forest communities in the south-western part of Poland.</p

Udział gatunków synantropijnych w zbiorowiskach z klasy Quercetea robori-petraeae Br.-Bl. et R.Tx. 1943 w Sudetach i na ich Przedgórzu. Occurrence of synanthropic species in forest communities of the class Quercetea robori-petraeae Br.-Bl. et R.Tx. 1943 in the Sudetes Mountains and foothills

<p>In 2009 and 2010, monitoring of conservation status and future prospects of the forest communities of Quercetea robori-petraeae Br.-Bl. et R.Tx. 1943 class was conducted in the Sudetes and their foothills. 31 sites were selected. At each site, three phytosociological releves were collected. An important component of the global assessment of oak forest communities is the occurrence of synanthropic species as measured by three indicators: occurrence of alien species (kenophytes), occurrence of synanthropic native species (apophytes) and occurrence of geographically alien tree species. At most sites, alien species and native expansive species were not observed or were represented by single specimens. For each site and releve, the index of synanthropization was calculated. The main role in the synanthropization of the investigated acidophilous oak forests is played by apophytes. The values for the synanthropization index suggest that this process is not advanced. However. the impact of synanthropization on species richness and floristic diversity of communities within oak forests is noticeable.</p

Siedliska przyrodnicze proponowanego obszaru Natura 2000 "Góra Wapienna"

<p>Naturhabitate des vorgeschlagenen Natura 2000–Gebietes</p> <p>„Góra Wapienna“ (Kalkberg) Zusammenfassung Das geschützte Gebiet „Góra Wapienna“ liegt zwischen Boberröhrsdorf (Siedlęcin) und Neu-Flachenseifen (Płoszczynka). Es umfasst die mehrgipflige Anhöhe des Kalkbergs (507 m) im südwestlichen Teil des Kleinen Kammes (Mały Grzbiet) im Bober-Katzbach-Gebirge (Góry Kaczawskie). Die schöne Natur des Kalkberges bewirkte, dass dieses Gebiet als einer der Bestandteile des Netzes Natura 2000 anerkannt wurde. Um mehr naturkundliche Kenntnisse über das vorgeschlagene Erhaltungsgebiet zu gewinnen, wurden innerhalb seiner Grenzen Untersuchungen durchgeführt. Sie betrafen die Lage, den Erhaltungszustand und die Differenzierung der Naturhabitate (gemäß des Annex zur I. Habitatsdirektive 92/43/EEC). Im Bereich des „Kalkberges“ wurde das Vorhandensein von 7 Typen von Naturhabitaten festgestellt. Das vorgeschlagene Erhaltungsgebiet nimmt eine Schlüsselstellung im Schutz der Habitate 9130 (fruchtbarer Buchenwald) und 6230 (Borstgras-Rasen) ein, die in der Sudetenregion zu den seltensten gehören. Der „Kalkberg“ ist auch von wesentlicher Bedeutung für den Schutz des Habitats 9170 (mitteleuropäische Eichen-Hainbuchenwälder) sowie des Habitats 6410 Siedliska przyrodnicze proponowanego obszaru Natura 2000 „Góra Wapienna” 50 (wechselfeuchte Wiesen). Die Naturhabitate in den Grenzen des Erhaltungsgebietes sind in gutem oder sehr gutem Zustand. Daher scheint es durchaus realistisch, diese Phytozenosen auch in der Zukunft erhalten zu können, und zwar unter der Bedingung, dass Vorkehrungen getroffen werden, die ihre Schutzerfordernisse erfüllen (das betrifft besonders halbnatürliche Habitate).</p> <p>Souhrn</p> <p>Chráněné území Góra Wapienna (Vápenná hora) se nachází mezi vesnicemi Siedlęcin a Płoszczynka v Kačavských horách (Góry Kaczawskie) na JZ části hřbetu Mały Grzbiet a rozkládá se na kopci o několika vrcholech s nejvyšší nadmořskou výškou 507 m. Přírodovědné hodnoty této lokality byly důvodem k tomu, aby byla vyhodnocena jako budoucí prvek sítě Natura 2000. Aby se rozrostly znalosti o přírodě daného území, byl tu prováděn výzkum, sledující rozšíření, stav a pestrost přírodních stanovišť, obsažených v příloze I směrnice 92/43/EEC o ochraněpřírodních stanovišť. Na území Góry Wapienné bylo potvrzeno sedm typů stanovišť. Vznikající chráněné území má zásadní význam pro ochranu stanovišť 9130 (květnatá bučina) a 6230 (smilkové trávníky), patřící v regionu Sudet k nejvzácnějším. Toto území má také důležitou roli v ochraně stanovišť 9170 (středoevropské dubohabřiny) a 6410 (střídavě vlhké bezkolencové louky). Přírodní stanoviště tu jsou ve stavu dobrém nebo velmi dobrém, a proto je reálné udržet fytocenózy Góry Wapienné i do budoucna. Pod podmínkou, že budou zajištěny ochranářské zásahy, které jsou pro udržení stavu nutné (což se týká zvláště stanovišť polopřirozených).</p